International Journal of Anatomy and Research, Int J Anat Res 2018, Vol 6(3.1):5458-63. ISSN 2321-4287 Original Research Article DOI: https://dx.doi.org/10.16965/ijar.2018.238 MORPHOMETRIC AND MORPHOLOGICAL STUDY ON THE SEPTO- MARGINAL TRABECULA Shrikanya M Shet *1, Kuldeep M D 2, Sheela G Nayak 3, V S Pare 4, Jyothi S R 5 , M P Shenoy 6. *1 Student, 1st MBBS, K V G Medical College, Sullia, Rajiv Gandhi University Of Health Sciences, Karnataka. 2 Student, 1st MBBS, K V G Medical College, Sullia, Rajiv Gandhi University Of Health Sciences, Karnataka. 3 Dean Academics, K V G Medical College, Sullia, Rajiv Gandhi University Of Health Sciences, Karnataka. 4 Professor and HOD, Department Of Anatomy, K V G Medical College, Sullia, Rajiv Gandhi Univer- sity Of Health Sciences, Karnataka. 5,6 Assistant Professor, Department Of Anatomy, K V G Medical College, Sullia, Rajiv Gandhi University Of Health Sciences, Karnataka. ABSTRACT Background and objectives: Moderator band is a specialized bridge present between the base of the anterior papillary muscle and interventricular septum. It carries the right branch of the bundle of HIS with it. The band is known to prevent the over distension of the right ventricle during the diastolic phase. There is a need of lot of research and studies on the septomarginal trabecula as it proves to be important clinically. Here we measured the length, breadth, height, angle with the interventricular septum, and the superficial marking of Moderator band on the sternocostal surface of the right ventricle is done. This paper describes the morphological variations found in its origin and insertion. Materials and Methods: 15 formalin-soaked cadaveric hearts were taken from the Department of Anatomy of KVG Medical College, Sullia. The foetal hearts, the hearts with gross pathology, if any are excluded from the study. Result: The morphometric parameters are tabulated and the morphological variations are noted. The results are compared with the results of the previous studies on the moderator band. Conclusion: It is confirmed that the thickness of moderator band varies at its origin and insertion. The surface marking of moderator band on sternocostal surface of the heart will help in locating the moderator band through the echocardiography and during cardiac surgeries on right ventricle. The possibility of second moderator band, multiple origin or insertion is more than 20%. KEY WORDS: Septomarginal trabecula, Surface marking, Right ventricle, Moderator Band. Address for Correspondence: Shrikanya M Shet, 1st MBBS, K V G Medical College, Kurunjibhag, Sullia, Dakshina Kannada, Karnataka, India. E-Mail: [email protected] Access this Article online Journal Information Quick Response code International Journal of Anatomy and Research ICV for 2016 ISSN (E) 2321-4287 | ISSN (P) 2321-8967 90.30 https://www.ijmhr.org/ijar.htm DOI-Prefix: https://dx.doi.org/10.16965/ijar Article Information Received: 30 Apr 2018 Accepted: 30 May 2018 Peer Review: 30 Apr 2018 Published (O): 05 Jul2018 DOI: 10.16965/ijar.2018.238 Revised: None Published (P): 05 Jul 2018 INTRODUCTION extends from the inter-ventricular septum to the The Moderator Band is a muscular band that base of the anterior papillary muscle. It takes Int J Anat Res 2018, 6(3.1):5458-63. ISSN 2321-4287 5458 Shrikanya M Shet, Kuldeep M D, Sheela G Nayak, V S Pare, Jyothi S R, M P Shenoy. MORPHOMETRIC AND MORPHOLOGICAL STUDY ON THE SEPTOMARGINAL TRABECULA. part in preventing over distension of right The presence of moderator band is one of the ventricle, hence the name “Moderator band” [1]. features which differentiates an anatomical right Despite many number of studies dedicated to ventricle from anatomical left ventricle [12]. The the moderator band, the controversies persist, histology of the moderator band was explained focussing mostly on its structure, function and by Turner [13]. The presence of moderator band evolutionary basis. In 1837 King.T.W [2] named in the ventricle is of high significance as the it as the “moderator band” as, according to his opening and closure of the atrioventricular concept, the trabecula limited the over-expan- valves is regulated by the anterior papillary sion of the right ventricle. muscle via chordae tendinae. It was Tandler .J [3] who first used the term A proper and good knowledge of the location, “Septomarginal trabecula”. He did this based on variations and surface marking of moderator the attachments of the moderator band. The band helps in various cardio-surgical procedures moderator band acts as a ‘marker’ for the right and in echocardiography. ventricle. It arises from the body of the inter- Here, in our study, the morphological parameters ventricular septum and crosses to are measured and the results are tabulated and the lateral wall of right ventricle. The modera- compared with results from previous studies. tor band is accompanied by a set of neuronal This study is helpful for radiologists and fibres from the right bundle branch of the atrio- anatomists in their studies regarding the ventricular conduction system [4]. It controls and moderator band. Also, the surgeons can more coordinates the contraction of anterior papillary efficiently correct the defects in the trabecula muscle. The right branch of ‘His’ bundle located by the knowledge of its morphology and varia- within the muscular part of the septum is tions associated [14]. continuous with the moderator band. The results MATERIALS AND METHODS of analyses have proved the presence of the Materials: 15 formalin soaked cadaveric speci- fascicle within the moderator band [5]. men of hearts were chosen from the Department Some probable ischemic pathologies of the of Anatomy, KVG Medical College, Sullia. The moderator band can cause critical disturbances foetal hearts, neonatal hearts, the hearts with in the conduction system of heart [6]. The gross pathology, if any, externally or internally moderator band artery anastomoses with are excluded from the study. The criteria like age various branches of the right coronary artery at and sex of the specimen were excluded from the base of the APM. It can play an important the study. Scalpel, toothed forceps, blunt-end role in the collateral circulation whenever this forceps and pointed forceps, needle pointer, circulation opens [7]. Collateral flow to the right digital vernier callipers, measuring tape, ventricular musculature, especially through the magnifying lens, transparent protractor, ordinary moderator band artery, protects against massive thread, pen torch, hand digital camera and infarction when there is occlusion in the proxi- markers were used during the study. mal right coronary artery [8]. An abnormal A parallel incision is placed along the upper moderator band can be a source of premature border of right ventricle, around 1.5 to 2cm ventricular contractions, monomorphic ventricu- below and to the right surface of the pulmonary lar tachycardia, and idiopathic ventricular fibril- trunk .Starting from the left end, the incision is lation [9]. extended till the right border. It was made sure Moderator band may be easily confused as a that the chordae tendinae were not cut. The in- mass near the apex of right ventricle [10]. cision is extended from the right end, downwards A 2-dimensional echocardiography can detect a .1cm parallel along the right border, the region superior shift in the position of the moderator of the right ventricle was cleaned thoroughly band. A possible risk of sub pulmonary obstruc- using cotton and water. Once the anterior papil- tion in those infants with a ventricular septal lary muscle is seen the incision from the left defect (VSD) can be predicted by the observa- upper end is done, in parallel and, 0.5 cm from tion in 2D echocardiography [11]. interventricular groove, tracing down extending Int J Anat Res 2018, 6(3.1):5458-63. ISSN 2321-4287 5459 Shrikanya M Shet, Kuldeep M D, Sheela G Nayak, V S Pare, Jyothi S R, M P Shenoy. MORPHOMETRIC AND MORPHOLOGICAL STUDY ON THE SEPTOMARGINAL TRABECULA. the incision to reach the origin of the moderator apex was measured using a measuring tape. band. It was made sure that the anterior papil- Also, the distance from the junction between lary muscle was not damaged by the incision. In right and inferior borders was noted using the specimen which had very thick walled right ven- measuring tape. tricle, the upper sternocostal wall is dissected Measurement of the superficial surface mark- and detached completely till proximal to the ing of the moderator band on the sternocostal papillary attachment. The blood clot is removed surface of the right ventricle is done by insert- with forceps and spray of water. ing a needle at the origin of the moderator band Measurement of the Length: The length of the from the inter-ventricular septum. Its distance moderator band is measured from the septal end from the right border which is at the junction at to the base of the anterior papillary muscle by right atrium between the opening of superior using either digital vernier callipers or by plac- and inferior vena cava and to the apex of the ing a thread throughout its course and measur- heart is measured. The apex of the heart and ing its length on scale. These methods help in the junction between inferior and right borders getting accurate measurements. of heart were marked separately. Measurement of the Thickness: The thickness Measurement of Height: The distance from of the moderator band was measured accurately the centre of the septal cusp to the base of using the digital vernier callipers at three dif- moderator band was considered as the height ferent segments. in the study. a. at the base i.e., the origin from the inter ven- Collection and recording of data: The measure- tricular septum ments are taken manually and noted down.